Electrically and/or thermally actuated release link

ABSTRACT

An electrothermal release detent that is equally responsive to either electrical or thermal stimuli which serves to release fire control apparatus such as a fire and/or smoke damper positioned within air-handling ducts or in other portions of building construction to thereby prevent the rapid spread of fire and smoke through the protected area.

United States Patent Raymond George Amicone Springfield;

Charles T. Davey, Dresher; Warren J. Dunning, Philadelphia, all of Pa. 849,8 1 1 Aug. 13, 1969 Oct. 19, 1971 Air Balance, Inc.

Chicago, 111.

inventors Appl. No. Filed Patented Assignee ELECTRICALLY AND/OR THERMALLY ACTUATED RELEASE LINK 18 Claims, 11 Drawing Figs.

US. Cl 169/42 Int. Cl A62c 37/30 Field of Search 169/ 1, 2, 26, 28, 42

References Cited Primary Examiner-Mv Henson Wood, .lr. Assistant ExaminerMichae1 Y. Mar Attorney-Karl L. Spivak ABSTRACT: An electrothermal release detent that is equally responsive to either electrical or thermal stimuli which serves 1 to release fire control apparatus such as a fire and/or smoke damper positioned within air-handling ducts or in other portions of building construction to thereby prevent the rapid spread of fire and smoke through the protected area.

PATENTEDUU 191971 3.613.795

SHEET 1 UF 2 INVENTORS fiaymzwm'eazye Km wane ar/es 7- 01 reg warren J, 01min! Km/x W ATTORNEY PATENTEDucT 19m n SHEET ESP 2 E SGTJ M N NE N EM W V AH IRCW ATTORNEY ELECTRICALLY AND/OR THERMALLY ACTUATED RELEASE LINK BACKGROUND OF THE INVENTION This invention relates to the general field of safety devices, and more particularly is directed to an electrically or thermally actuated release detent suitable for operation with fire and smoke dampers.

Duct systems for air-handling purposes have traditionally been constructed in buildings as one of the many usual design features and such systems in the past have formed a basis for considerable engineering research and technical improvements. Prior workers in the art have found that very often when designing air-conditioning systems, air distribution design considerations have required that duct work pass through firewalls, fire partitions, floors, shafts, separations between occupancies and other special areas such as mechanical equipment rooms. In such locations, most building codes and other safety standards require the installation of fire dampers to prevent the possible spread of heat and flame from one fire division area to another through the duct work itself. Accordingly, design engineers, mechanical contractors, and other prior workers in the art have employed fire dampers to provide the necessary fire protection devices at the critical Iocations so designated by present safety standards.

Recently, tests have been conducted and investigations made of actual fires and it has been determined that in most instances, buildings subject to fire become untenable from smoke long before they are untenable due to elevated temperatures. Because of this added awareness, much thought has been given recently to personnel protection in buildings and safety from smoke considerations now form an important building design parameter. However, despite the knowledge that smoke can be a killer, to this date, numerous smoke detection devices have been developed to trigger alarms to thereby warn building occupants, but as of this time, no satisfactory smoke damper has been developed to actually prevent the spread of smoke through duct work from area to area. Inasmuch as the products of combustion pouring through ventilating ducts usually present a greater peril than the fire itself to personnel trying to escape from a fire, the rapid detection and prompt isolation of smoke and fumes by closing smoke dampers in ventilating ducts can add a greatly improved weapon in the constant war against danger from fire.

Presently available fire dampers usually contain damper blades or shutters which are spring activated and are held in the open position by a fusible link responsive to the heat of a fire. When the temperature in the duct is increased by the fire, the link melts and the blades or shutters close to thereby isolate a section of the duct work. These prior art dampers, however, are completely ineffective to prevent the passage of smoke unless the smoke is accompanied by adequate heat to activate the fusible link.

SUMMARY OF THE INVENTION The rapid detection and prompt isolation of smoke and fumes by closing dampers in ventilation ducts can save precious moments that may mean the difference between like and death for the occupants of a building. The present electrically and/or thermally actuated release link will furnish an effective, low-cost solution for the problem of providing rapid closure of present fire damper designs immediately upon sensing the presence of smoke. The instant device is highly sensitive and rapidly responsive to electrical signals which permit operation of the device in combination with a variety of smokeand fire-detecting instruments that are currently available. For example, an ionization detector or heat detector of known design located in a critical space of a building could be wired to furnish a small electric current to a plurality of electrothermal detents which could be located in various strategic locations within the building ductwork to thereby permit prompt isolation of the fire and smoke by closing the associated fire dampers.

The present device incorporates an electrothermal detent which is equally responsive to actuation either by elevated temperatures or by external stimuli. The device includes two structural members which serve as a detent for opposing forces and which are joined together by fusible material that melts within a desired temperature range. The device further includes an electrical transducer that triggers the release of stored chemical energy which serves to raise the temperature of the detent above the melting temperature of the fusible material to thus separate the two structural members. Additionally, the fusible material is also responsive to the direct application of heat in the usual manner. Further, when desirable, a self-contained integral detection device and power source may be included to thus provide a unitary structure.

Thus, a new and practical device has been provided that will function upon the application of either thermal or electrical stimuli to trigger or release a restrained force such as may be applied by a spring loaded or gravity actuated fire damper. The use of the present electrothermal detent will permit substantially instantaneous closure of all presently known fire damper designs.

It is accordingly a primary object of the present invention to provide an apparatus for restraining the operation of a fire or smoke control device and which releases such operation upon the occurrence of either excessive heat or undesirable change in environmental condition.

It is a further object to provide an apparatus to thereby release a fire safety device. Additionally, it is an additional purpose of this invention to provide a device that will be equally responsive to the presence of heat to thereby actuate a fire safety device.

In particular, it is an object of this invention to provide an electrothermal detent which is responsive to a variety of smokeand fire-detecting devices that are currently available.

Furthermore, it is another object of the invention to provide an electrothermal detent including an electrical transducer capable of changing electrical energy into heat energy to thereby melt fusible material to thus separate the detent section.

It is also an object of the present invention to provide an electrothermal detent that is capable of operation with either self-contained or remotely located detectors capable of producing sufficient electrical energy for transducer operation.

In addition, it is a further object of the invention to provide a combination smoke and fire damper which will function upon the application of either a thermal or electrical stimulus to trigger or release a restrained force such as applied by a spring-loaded blade or shutter in a fire damper.

It is a further object of the present invention to provide an electrothermal detent that is rugged in construction, simple in design and trouble free when in operation.

Other objects and a fuller understanding of the invention will be had by referring to the following description and claims of a preferred embodiment thereof, taken in conjunction with the accompanying drawings wherein like reference characters refer to similar parts throughout the several views and in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a partial, side elevation view of an electrothermal detent holding a plurality of damper blades in the open position.

FIG. 2 is a view of the damper blades of FIG. I in closed position after firing of the electrothermal detent.

FIG. 3 is an enlarged, top plan view of an electrothermal detent.

FIG. 4 is a side elevational view of the detent of FIG. 3.

FIG. 5 is an exploded, perspective view of the detent of FIG. 3.

FIG. 6 is a cross-sectional view taken along Line 6-6 of FIG. 3, looking in the direction of the arrows.

FIG. 7 is a schematic wiring diagram.

FIG. 8 is a partial, side elevational view of a modified electrothermal detent holding a plurality of damper blades in the open position.

FIG. 9 is an enlarged, top plan view of a modified electrothermal detent.

FIG. 10 is a side elevational view of the electrotherrnal detent of FIG. 9.

FIG. 11 is an enlarged top plan view of a modified electrothermal detent.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of our invention selected for illustration in the drawings and are not intended to define or limit the scope of the invention.

Referring now to FIGS. 1 and 2, we show a fire damper 10 of conventional design including a plurality of damper blades l4, 16 which pivotally rotate about the shafts 12, 18 from the open position as illustrated in FIG. I to the closed, fire and smoke retarding position as illustrated in FIG. 2. Operating linkage 20 of any well-known workable construction operates the blades l4, 16 in unison by means of the vertical tie bar 22. A spring (not shown) generally operates in conjunction with the operating linkage 20 to bias the vertical tie bar 22 downward to thereby urge the blades l4, 16 to their closed position. See FIG. 2. A separable heat-responsive link 28 secures at one end thereof to the vertical tie bar 22 and at the other end thereof to a portion of the stationary fire damper frame 30 and acts as a detent to thereby lock damper blades 14, 16 in their open position as in FIG. 1 against the forces tending to close the damper blades such as the bias of a tie bar connected spring (not shown) or in some designs, against the forces of gravity.

Referring now to FIGS. 3, 4, and 6, we show the construction of one embodiment of a heat-responsive link in detail. A pair of similar, separable, structural members 32, 34 separately secure together in fused relation over the cylindrical heatgenerating means 36. The structural members 32, 34 each terminate outwardly in a connector loop 38, 40 which extend in opposed relation to readily permit connection therein of the damper-retaining cords 42, 44 as best seen in FIG. 1. The cords 42, 44 maintain the damper blades 14, 16 in the open position by separably connecting the tie bar 22 to the damper frame 30 in the usual manner. The connector loops 38, 40 respectively integrally inwardly join the semicylindrically formed fastening sections 46, 48 which are shaped as required to closely overfit the configuration of the heat-generating means 36 in substantially complete peripheral engagement. As best seen in FIG. 6, the fastening sections 46, 48 affix to the outer peripheral surface of the heat-generating means 36 through a thermally responsive material having a relatively low melting point such as solder. The metallic alloy 50 is similar to the solder compounds now in use in connection with conventional fusible detents in presently used fire dampers (such as Woods metal) and preferably melts at a temperature in the range of 125 to 165 F. for ordinary use, 175 to 212 F. for intermediate use and 250 to 286 for high-temperature use. It will be appreciated that a higher melting point material should be employed where the fire damper will be installed in an area having relatively high ambient temperature conditions. The detent 28 operates as a conventional fusible link to release the operation of the fire control device whenever the temperature exceeds the melting point of the fusible material 50. In addition, the detent operates under external stimuli applied to the heat generating means 36. As best seen in FIG. 6, the fastening section longitudinal edges 52, 54 of the separable members 32, 34, preferably do not touch to thereby minimize the possibility of imperfection in manufacture and jamming when in use by providing a construction which assures fabrication utilizing precisely the proper quantity of solder 50.

The heat generating means 36 are preferably cylindrically formed and are specifically designed not to rupture upon activation. Pyrotechnic heaters, type T-24El or T-65 as manufactured by Atlas Chemical Industries, Inc., have been found suitable for the purpose. We have found that heat generator dimensions of diameter of one-quarter of an inch and a length of five-eighths of an inch is suitable to provide a bond with the structural members of adequate strength to withstand the usual tension stresses, which normally will not exceed 30 pounds. The electrothermal detent as constructed in accordance with the present invention has been tested for mechanical strength and has proved satisfactory and reliable in all instances. The results of these mechanical tests are set forth below in chart I:

Electric current introduced to the heat-generating means through the insulated lead wires 56, 58, triggers the heatgenerating means 36 which, by exothermic chemical reaction acts to rapidly generate sufficient heat to thereby melt the connecting solder layer 50 between the heat-generating means 36 and the separable structural members 32, 34. Upon melting of the fusible material 50, the forces acting upon the fire damper operating linkage 20 separate the structural members 32, 34 to cause the damper blades 14, 16 to rotate to the closed position of FIG. 2. The response of the heat-generating means 36 following the application of electrical current transmitted through the circuit 61 upon activation of the detector 66 is substantially simultaneous, resulting in the generation of sufficient quantities of heat for solder melting purposes in a fraction of a second. Tests have proved the reliability of the design as set forth below in chart ll wherein sample electrothermal detents were tested for electrical activation. The electrotherrnal heaters 36 function in conjunction with power sources of twelve volts or less supplied through a transformer 64 and are sufficiently sensitive to positively respond upon application of small electrical currents.

CHART II Sample NO. Type of Separated Heat Generator T-24El Yes Yes Yes Yes

Yes

Yes

Yes

Yes

Yes

Yes

It should be noted that the heat responsive link 28 is fabricated to provide a unitary structure at usual room temperatures by means of a metallic alloy 50 which secures the semicylindrical sections 46, 48 to the cylindrical heat-generating means 36. Therefore, the individual elements comprising the link 28 may be separated either by the application of external heat of sufiiciently high temperature to melt the alloy 50 or else upon the application of electrical current to trigger the heat-generating means 36 which then generates sufficient heat to thereby melt the alloy 50. Accordingly, the link elements are equally separable either upon the application of elevated temperatures in the vicinity of the link or upon receipt of electrical signals such as may be generated by an external heat or smoke detection device mounted in a remote location.

As shown in FIG. 7, the heat-responsive detent 28 may be wired into the electrical circuit 61 through the lead wires 56, 58 which connect in a series circuit. The usual 1l0-volt alternating current is applied at the terminals 60, 62 in the usual manner to power the circuit 61 through a step down transformer 64 in well-known manner. Alternately, direct current battery current may be employed, also in well-known manner. A detector 66 connects in series with the circuit 61 to thereby trigger the heat generating means 36 upon detection of previously designed conditions of smoke or elevated temperature. The detector 66 may be responsive to either heat or smoke and is normally located in an area remote from the heat responsive detent 28 such as in a room, closet or other divided area removed from the immediate vicinity of the duct (not shown) wherein the fire damper is positioned. The detector 66 may be of the type responsive to heat such as the usual fixed temperature or rate of rise of heat detector or may be responsive to smoke such as commonly in use in presently available electric eye type or ionization type smoke detectors.

In another embodiment of our invention, we show a modified electrothermal link 28' applied to a fire damper 10 of the folding interlocking blade design. Referring now to FIGS. 8-10, we show the electrothermal link 28 serving as a detent to restrain the fire damper blades 14', in their open position.

A pair of similar, separable, structural members 32', 34' separatively secure together in fused relation over the cylindrical heat-generating means 36'. The structural members 32', 34' each terminate outwardly respectively in a connector loop 38', 40' which extend in opposed relation to readily permit connection therein of the damper retaining cords 42', 44', as best seen in FIG. 8. The cords 42, 44' maintain the damper blades 14', in the open position by separatively connecting the loops 38, 40 to the damper frame beneath the blades in well-known manner.

The connector loops 38, respectively inwardly join the structural members 32', 34' to impress outwardly opposing forces thereon. The members 32', 34 respectively inwardly terminate in transverse, semicylindrically formed fastening sections 46, 48 which are shaped as required to closely overfit the configuration of the heat-generating means 36 in substantially complete peripheral engagement. See FIGS. 9 and 10. A low melting material 50' such as Wood's metal which possesses the required strength to cement the members 32, 34' together over the heat-generating means 36' at usual room temperatures and additionally possesses a low enough melting temperature to fuse upon elevated temperatures in the range of 125 to 165 F. for ordinary use, secures the operating parts together. The insulated lead wires 56', 58 connect heatgenerating means 36' into the electrical circuit 61 in the usual manner.

Referring now to FIG. 11, we show another modified form of electrothermal link 70 comprised of a unitary length of thermally sensitive plastic material, such as a strip of polyvinylchloride plastic. The link 70 includes a narrow neck section 72 which terminates at each end thereof in a structural tab 74, 76 respectively. Each tab 74, 76 is pierced near the ends thereof to provide a cord connection opening 78, 80. An electrical heater 82 coils about the neck section 72 to supply sufficient heat to melt through the neck section 72 upon energization of the heater 82. Thus, the electrical heater 82 may similarly be wired into the electrical circuit 611 to thereby sever a detent 70 upon the introduction of the necessary environmental stimuli to trigger the detector 66.

We claim:

1. In a smoke or fire control device to prevent the spread of smoke or fire within a structure, the combination of,

A. smoke or fire control means operable from a fist position to a second position;

B. a heat-separable detent securing the smoke or fire control means in the said first position;

C. heat-generating means associated with the said detent,

1. operation of said heat-generating means being initiated by stimulus generating means,

2. said heat-generating means being capable of generating sufficient heat to separate the said detent; and

D. stimulus generating means functioning upon the presence of smoke or fire,

1. said stimulus generating means sending initiating stimuli to the said heat-generating means, whereby the said detent separates upon presence of smoke or fire to thereby permit the smoke or fire control means to operate from the first position to the second position.

2. The invention of claim 1 wherein the said heat-generating means are initiated by electrical stimuli.

3. The invention of claim 1 wherein the said heat-generating means include an electrical transducer.

4. The invention of claim ll wherein the said stimulus generating means also function upon the presence of elevated temperatures.

5. The invention of claim 1 wherein the said heat-separable detent is operably responsive either to heat produced by the said heat-generating means or by elevated temperatures present in the vicinity of the said detent.

6. The invention of claim 1 wherein the smoke and fire con trol device is a fire damper.

7. The invention of claim 1 wherein the smoke and fire control device is a fire door.

8. The invention of claim 1 wherein the smoke and fire control device is a sprinkler head.

9. The invention of claim I wherein the smoke and fire control device is a compressed gas release valve.

10. In a heat-responsive detent, the combination of A. separable structural means,

1. said structural means including semicylindrically formed fastening sections,

2. said structural means being provided with fusible means,

a. said fusible means securing said fastening sections together at normal ambient operating temperature, b. the said fusible means melting upon the occurrence of temperature elevated above said normal ambient operating temperature; and

B. heat-generating means associated with said fusible means,

I. said heat-generating means being capable of generating sufficient heat to melt said fusible means thereby releasing said fastening sections from each other.

111. The invention of claim 10 wherein the fastening sections substantially enclose the heat-generating generating means.

12. The invention of claim 11 wherein the heat-generating means include an electrical transducer.

13. The invention of claim 10 wherein the fusible means melt in response either to heat produced by the heat-generating means or to elevated temperatures present in the vicinity of the fastening sections.

14. The invention of claim 10 wherein the detent has a longitudinal axis between its ends and the semicylindrically formed sections have their cylindrical surfaces aligned with the said axis.

15. The invention of claim 10 wherein the detent has a longitudinal axis between its ends and the semicylindrically formed sections have their cylindrical surfaces directed transversely of said axis.

16. In a heat-responsive detent, the combination of A. separable structural means,

I. said structural means including a pair of fastening sections,

2. said structural means being provided with fusible means,

a. said fusible means being disposed between said fastening sections and securing said fastening sec- 2. said heat-generating means being capable of generating sufficient heat to melt said fusible means thereby releasing said fastening sections from each other.

17. The invention of claim 16 wherein said fastening sections have surfaces mating with surfaces of the heat-generating means enclosed thereby.

18. The invention of claim 17 wherein said fastening sections are similar. 

1. In a smoke or fire control device to prevent the spread of smoke or fire within a structure, the combination of, A. smoke or fire control means operable from a fist position to a second position; B. a heat-separable detent securing the smoke or fire control means in the said first position; C. heat-generating means associated with the said detent,
 1. operation of said heat-generating means being initiated by stimulus generating means,
 2. said heat-generating means being capable of generating sufficient heat to separate the said detent; and D. stimulus generating means functioning upon the presence of smoke or fire,
 1. said stimulus generating means sending initiating stimuli to the said heat-generating means, whereby the said detent separates upon presence of smoke or fire to thereby permit the smoke or fire control means to operate from the first position to the second position.
 2. said heat-generating means being capable of generating sufficient heat to separate the said detent; and D. stimulus generating means functioning upon the presence of smoke or fire,
 2. The invention of claim 1 wherein the said heat-generating means are initiated by electrical stimuli.
 2. said structural means being provided with fusible means, a. said fusible means securing said fastening sections together at normal ambient operating temperature, b. the said fusible means melting upon the occurrence of temperature elevated above said normal ambient operating temperature; and B. heat-generating means associated with said fusible means,
 2. said structural means being provided with fusible means, a. said fusible means being disposed between said fastening sections and securing said fastening sections together at normal ambient operating temperature, b. said fusible means melting upon the occurrence of temperature elevated above said normal ambient operating temperature; and B. heat-generating means associated with said fusible means,
 2. said heat-generating means being capable of generating sufficient heat to melt said fusible means thereby releasing said fastening sections from each other.
 3. The invention of claim 1 wherein the said heat-generating means include an electrical transducer.
 4. The invention of claim 1 wherein the said stimulus generating means also function upon the presence of elevated temperatures.
 5. The invention of claim 1 wherein the said heat-separable detent is operably responsive either to heat produced by the said heat-generating means or by elevated temperatures present in the vicinity of the said detent.
 6. The invention of claim 1 wherein the smoke and fire control device is a fire damper.
 7. The invention of claim 1 wherein the smoke and fire control device is a fire door.
 8. The invention of claim 1 wherein the smoke and fire control device is a sprinkler head.
 9. The invention of claim 1 wherein the smoke and fire control device is a compressed gas release valve.
 10. In a heat-responsive detent, the combination of A. separable structural means,
 11. The invention of claim 10 wherein the fastening sections substantially enclose the heat-generating generating means.
 12. The invention of claim 11 wherein the heat-generating means includE an electrical transducer.
 13. The invention of claim 10 wherein the fusible means melt in response either to heat produced by the heat-generating means or to elevated temperatures present in the vicinity of the fastening sections.
 14. The invention of claim 10 wherein the detent has a longitudinal axis between its ends and the semicylindrically formed sections have their cylindrical surfaces aligned with the said axis.
 15. The invention of claim 10 wherein the detent has a longitudinal axis between its ends and the semicylindrically formed sections have their cylindrical surfaces directed transversely of said axis.
 16. In a heat-responsive detent, the combination of A. separable structural means,
 17. The invention of claim 16 wherein said fastening sections have surfaces mating with surfaces of the heat-generating means enclosed thereby.
 18. The invention of claim 17 wherein said fastening sections are similar. 